How much water does a rat drink? - briefly
An adult laboratory rat weighing about 250–300 g usually consumes 30–50 ml of water daily (≈10–15 ml per 100 g body weight). Intake rises with higher temperature or increased metabolic demand.
How much water does a rat drink? - in detail
Rats typically consume between 30 ml and 45 ml of water per 100 g of body weight each day. For an adult laboratory rat weighing 250 g, this translates to roughly 75 ml–110 ml (approximately 2.5 fl oz–3.7 fl oz) of fluid per 24 hours.
Key determinants
- Body mass – water intake scales with weight; larger individuals require more fluid.
- Ambient temperature – each 5 °C rise above 20 °C can increase consumption by 10‑15 % because of higher evaporative loss.
- Dietary moisture – rats fed wet mash or fresh produce obtain a portion of their needs from food, reducing drinking volume by 20‑30 % compared with dry pelleted diets.
- Sex and reproductive status – lactating females may double their intake to support milk production; males and non‑reproductive females show similar baseline values.
- Strain differences – outbred strains (e.g., Sprague‑Dawley) generally match the cited range, while some inbred lines (e.g., Wistar) exhibit slightly lower consumption, around 25 ml per 100 g.
Typical experimental observations
| Strain | Weight (g) | Daily water intake (ml) |
|---|---|---|
| Sprague‑Dawley | 250 | 80 – 110 |
| Wistar | 250 | 70 – 95 |
| Long‑Evans | 300 | 95 – 130 |
Practical implications for husbandry
- Provide fresh water at all times; a 250 ml bottle generally suffices for a group of 4–5 adult rats under standard conditions.
- Monitor intake during temperature spikes or when diet changes; a sudden drop may signal illness or dehydration.
- Adjust volumes for neonates and juveniles; pups under 30 g consume roughly 5 ml kg⁻¹ day⁻¹, increasing sharply after weaning.
In summary, a rat’s fluid requirement is primarily a function of its mass, environmental heat load, and moisture content of its diet, with typical adult consumption ranging from 75 ml to 110 ml per day for a 250 g animal.